Acknowledgement
We thank Prof. Masaki Sasaki, Dr. Takuya Kiyoshi and Mr. Yuya Matsuo for helping with this research.
Funding
This work was supported by a grant from Ministry of Agriculture, Forestry and Fisheries of Japan (Research project for Monitoring and enhancement of pollinators for crop production).
Supplementary material
Supplementary Video 1 is included for this article at: http://dx.doi.org/10.1080/0005772X.2018.1556964.